"It's one of those jobs that you have to take year by year, it's ten months a year, it's all-consuming," he told talkshow host Jonathan Ross. "So I don't think you can plan five or six years ahead, or even two years ahead.

"It's a year by year thing, and at the moment it's 2013 and we'll see what 2014 holds."

Away from Doctor Who, Smith's recent roles have included two BBC biopics. He played novelist Christopher Isherwood in Christopher and His Kind in 2011, and starred as Olympic gold medal-winning rower Bert Bushnell in last summer's Bert and Dickie.

Gosling is also directing the fantasy thriller, which counts Eva Mendes, Saoirse Ronan and Mad Men's Christina Hendricks among its cast.

Filming on the 50th anniversary special of Doctor Who is due to begin next month, and the show returns to BBC One in the UK and BBC America in the US a week on Saturday (March 30) with new episode 'The Bells of Saint John'.

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'The Bells of St John' will open the next run of Doctor Who episodes on March 30. The Steven Moffat-penned episode is set in contemporary London.
Copyright: BBC Adrian Rogers / Ray Burmiston
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